Well, as I said it's best to have fiat (shitcoin) for this one. Which is why I won't do it. But, basically you buy however many BTC on the spot for current price of 55000. At the exact same time you sell a future, perhaps Sep 26th for this example, for the same number of BTC at a current price of 62700. profit equals 7,700 minus fees per coin

This can be done using CBOE and CME as well as many others, perhaps less reputable exchanges.

The risk for this trade is couter-party only and of course opportunity cost (there is no possiblity of capital gains or losses). Not your keys not your coins. Thing is it's all about levels of risk and what you are comfortable with in the end as well as your goals. Just remember nothing is risk free. Even holding your own keys is not risk free, there are roughly 4million inaccessible coins to prove that.

*Above prices are taken from Deribit.